The NFL and NFL Players Association for the first time have banned specific helmets for use, saying those models performed poorly in its annual testing procedures or are no longer supported by their manufacturers.

Ten helmet models have been targeted for phaseout, six immediately and four by the start of the 2019 season. Approximately 200 NFL players wore one of those models in 2017, according to Jeff Miller, the NFL’s executive vice president of health and safety initiatives.

The NFL has been ranking helmets, from best- to worst-performing based on laboratory testing, for four years. On Monday, teams and players received the 2018 rankings, which are topped by two models from VICIS, a company that was founded in 2013.

“Over the last few years, we’ve seen some dynamic changes in the helmet industry,” Miller said. “We’ve seen a number of new helmets enter the market from both new innovators, as well as new helmet models from incumbent companies, which means that there are a number of helmets for players to move to.

“And we’ve begun to see that over the last couple of years, players [are] moving from helmets that rank in the poorly performing areas to those that are ranging closer to the top-performing helmets. We think that is an important move, and we think that will improve player health and safety. And the purpose of continuing to rank the helmets, and the purpose of the joint decision to prohibit certain helmets this year, is to increase that continued movement into better-performing helmets.”

Thirty-four helmets were tested for the 2018 rankings. They came after a season in which NFL players suffered 291 concussions, the highest number on record. NFL chief medical officer Dr. Allen Sills called that number “unacceptable” and declared a “a call to action” in February to address it.

League owners agreed in March to a significant rule change that will threaten immediate ejections anytime a player lowers his helmet and initiates contact with another player. The kickoff is under heavy scrutiny after it was determined to cause concussions at five times the rate of an average play, and plans are underway to work with teams to address a spike in concussions caused during training camp scrimmages.

Dr. Jeff Crandall, the chairman of the NFL’s engineering committee, said the helmet testing recreated 24 conditions that typically occur on NFL playing fields. It measures “a number of accelerations and motions of the head,” Crandall said. Helmets are ranked on how they “manage the forces” that players most often come into contact with, he added.

The tests and new policy were carried out in conjunction with Crandall, Miller and Dr. Kristy Arbogast, who is co-scientific director and director of engineering for the Center for Injury Research and Prevention at Children’s Hospital of Philadelphia and an adviser to the NFLPA.